I read somewhere not long ago that Silkies are really very cold hardy. Here's a link to a different conversation regarding silkies and cold hardiness https://www.backyardchickens.com/t/...-are-more-cold-hardy-than-we-tend-to-think/10
We had several 20 years ago in warmer climate of NM, and am trying again now, but our little roo died last week (on a fairly warm day). We get so cold and windy up here, I tried to really check it out before diving in.
Once feathered they do seem to stay nice and toasty, but it sometimes takes them a bit longer than smooth feathered breeds to grow a full set of feathers. I have mine out in the unheated, uninsulated coop and they seem quite content. They snuggle together at night, but they do that all the time, regardless of weather.